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SLi Blown PSU?

AiiR

AiiR

AiiR

Soldato
Joined
19 Feb 2009
Posts
3,373
Just added a 2nd Gigabyte 970 to my system, and I just want to get it in early that I know what I've done here is beyond stupid but whats done is done. :D

Added the 2nd GPU, now I have a Corsair CS750M is the system currently, which after doing some research seemed adequate for dual 970's. The unit only has enough PCIe connections for 1 card, so I utilised the molex connections that came in the box to hook the 2nd one up (its up for debate whether or not this was a sensible solution, but they were in the box so I assumed they'd be fine).

This is where the stupidity happens..

So I hooked the card up using all 4 molex connections on a single daisy chain, so it was drawing all its power from a single plug on the supply. I didn't realise the error of my ways until I hit the power switch and sparks flew from the power supply.

So it seems to be dead now, and I've now learnt not to whack everything on to a single supply module bit. However, my question is how common is this? Surely I'm not the first person to do it, is it really that easy to kill off a power supply or would it have been on its way out anyway?
 
Something wrong with the PSU, while I wouldn't recommend doing what you did, it shouldn't have blown the PSU as it's looks like a single rail design like most PSUs these days.

62A from the +12 v should be ample to power the sli setup. If there was a dodgy wire shorting your connection that would explain why it blew up.
 
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Sasahara said:
Something wrong with the PSU, while I would recommend doing what you did, it shouldn't have blown the PSU as it's looks like a single rail design like most PSUs these days.
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That was my thought, I'd understand if it blew if I fired up furmark or Crysis but it was the moment I hit the power button.. Shame as the PSU is less than a year old, so off to the RMA centre I think!

That aside, I've now ordered a Corsair RM850X so it'll atleast have some dedicated PCIe power for both.
 
Never skimp on a PSU, it is one of the cheapest parts of your system but can do a lot of damage if not up to the job.

When deciding on a PSU get one that has 400 watts+ over what you need. This will leave room for upgrades and the PSU will run silently most of the time as it will not be stressed.

PSUs also run most efficiently when used near half their max output.
 
Because I dont like over stressing my PSU plus prefer it having the fan runninging quietly, i always aim to get a psu with double the W i need. Eg If i work out I need 500W then I buy a 1000W psu.

Dont forget over time PSU's supply less and less power slowly as well.

Just because a 750W can supply 750W of power doesnt mean that you should do that 24/7.

The way I look at it is like a car. It might rev to 6000 rpm but you wouldnt drive it 24/7 at 6000rpm all day and expect it to last as long as another engine only doing 3000rpm.
 
At the time I didn't think spending £80 on a Corsair power supply was skimping, are these models to be avoided then?
 
I've seen a cx750m corsair running Daul 970's no problems (does have 4 x 6+2 pcie connections direct from psu) . Never use adapters if possible to avoid any potential issues.
 
I think you have just been unlucky and connecting them to the same line wasn't a good idea, contre to what was said above I think most PSU's are now multi'rail or multi'rail capable and should be run so, my RM850i is.
 
The cx series of power supplies are hit and miss, they are cheaper components and sometimes don't last long. I bought one for my old system and it lasted 2 weeks. Would never use one for my main rig.
 
I wouldnt call a cx750 skimping, psu's are not cheap now days, e.g. if I got a psu that was 1000 watts instead of the 600watts I have then I very likely wouldnt have afforded the gpu/cpu setup I have now as the extra money on the psu would have had to come out of another pc component.
 
Depends how you look at it, I would never put anything like that in my main rig simply because the components used are poor in comparison to the higher end psu's. The psu is the most important component so why use a poor psu?
 
AdamScott85 said:
Depends how you look at it, I would never put anything like that in my main rig simply because the components used are poor in comparison to the higher end psu's. The psu is the most important component so why use a poor psu?
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Agreed , seems easy to skimp and save £30 on a PSU but false economy.

The last one to go on me, and it was an EVGA one, took out my cpu and moboboard. Luckily both got replaced under warranty.

So i do my research on psu and always use Johnnyguru for his hot box tests.

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=416

Not the greatest of reviews, he refers to it being not a bad 600W psu despite being labelled a 750W and when hot it shuts down over 600W load.

Poor build quality, poor soldering and in his one he tested they had managed to nip one of the wires putting it together and had got through to bare wire which might result in a short.
 
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Well it looks like the motherboard has gone as well as now there's a popping sound coming from the vrm area
Dayum. I knew SLi was a pain but not this bad!
 
AiiR said:
Well it looks like the motherboard has gone as well as now there's a popping sound coming from the vrm area
Dayum. I knew SLi was a pain but not this bad!
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Not really the fault of sli but the PSU

When my PSU blew it should have had all the protection about power drain and shorting out. The woes actually melted that connect into the motherboard and the whole lot fried including the cpu. Luckily the Gpus and memory lived.

After that I swore that since I can easily have over a grand of stuff in October, skimping on PSU is a no no. And like you I thought I hadn't skimped by buying a good brand and it seemed to have enough power, 750w.

So now I go big and running what was at the time, the most highly rated PSU on johnnyguru. I worked out overclocked I needed 700w max so went for 1200w.

Has lasted me years now and has never missed a beat even when I went xfire or sli.
 
Greebo said:
Not really the fault of sli but the PSU

When my PSU blew it should have had all the protection about power drain and shorting out. The woes actually melted that connect into the motherboard and the whole lot fried including the cpu. Luckily the Gpus and memory lived.

After that I swore that since I can easily have over a grand of stuff in October, skimping on PSU is a no no. And like you I thought I hadn't skimped by buying a good brand and it seemed to have enough power, 750w.

So now I go big and running what was at the time, the most highly rated PSU on johnnyguru. I worked out overclocked I needed 700w max so went for 1200w.

Has lasted me years now and has never missed a beat even when I went xfire or sli.
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Yeah I know it was the PSU, most definitely. And I agree, especially with some of them having 7 years warranty and more, no reason to not get a high end power supply when it's guaranteed to last that long. This experience has opened my eyes to what is really a good power supply.
 
To mirror what a few have said already, the PSU is the most important part of a system and never skimp, for me it is always either superflower, seasonic, antec or evga(most are now superflower oem), i personally would never buy a corsair PSU, owned a AX860i once and sold it 4 weeks later, dont get me wrong there fine as long as your not stressing them, i was getting constant shutdowns etc, switched out for a seasonic model at that time with the same power output and never had a problem.
 
Nickolp1974 said:
To mirror what a few have said already, the PSU is the most important part of a system and never skimp, for me it is always either superflower, seasonic, antec or evga(most are now superflower oem), i personally would never buy a corsair PSU, owned a AX860i once and sold it 4 weeks later, dont get me wrong there fine as long as your not stressing them, i was getting constant shutdowns etc, switched out for a seasonic model at that time with the same power output and never had a problem.
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Yet -> http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story6&reid=317

Can you find us a crap review score for an AX860i from someone we can trust?
 
LeMson said:
Yet -> http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story6&reid=317

Can you find us a crap review score for an AX860i from someone we can trust?
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Just my opinion from my own experience, like i said good units but for me not when pushed and this was within its rated limits. Take my superflower 1200 plat for instance, this didn't crap out until around 1440W, this was with 2x 780 classifides.
Hmm someone you can trust?? Maybe 8Pack can coment if he reads this?

At the end of the day it all depends on the users needs like any component, if your gaming, light benchmarking etc then the AX will be more than upto the job but if your someone whom likes to push a little harder then i stand by my coment and i would not buy one.
 
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